Add redis database backend

db-redis.cpp

@@ -0,0 +1,165 @@
+#include <stdexcept>
+#include <sstream>
+#include <fstream>
+#include "db-redis.h"
+#include "types.h"
+
+static inline int64_t stoi64(const std::string &s)
+{
+	std::stringstream tmp(s);
+	int64_t t;
+	tmp >> t;
+	return t;
+}
+
+
+static inline std::string i64tos(int64_t i)
+{
+	std::ostringstream os;
+	os << i;
+	return os.str();
+}
+
+inline std::string trim(const std::string &s)
+{
+	size_t front = 0;
+	while(s[front] == ' '    ||
+	      s[front] == '\t'   ||
+	      s[front] == '\r'   ||
+	      s[front] == '\n'
+	     )
+		++front;
+
+	size_t back = s.size();
+	while(back > front &&
+	      (s[back-1] == ' '  ||
+	       s[back-1] == '\t' ||
+	       s[back-1] == '\r' ||
+	       s[back-1] == '\n'
+	      )
+	     )
+		--back;
+
+	return s.substr(front, back - front);
+}
+
+#define EOFCHECK() \
+ 	if(is.eof()) \
+		throw std::runtime_error("setting not found");
+
+std::string get_setting(std::string name, std::istream &is)
+{
+	char c;
+	char s[256];
+	std::string nm, value;
+
+	next:
+	while((c = is.get()) == ' ' || c == '\t' || c == '\r' || c == '\n')
+		;
+	EOFCHECK();
+	if(c == '#') // Ignore comments
+		is.ignore(0xffff, '\n');
+	EOFCHECK();
+	s[0] = c; // The current char belongs to the name too
+	is.get(&s[1], 255, '=');
+	is.ignore(1); // Jump over the =
+	EOFCHECK();
+	nm = trim(std::string(s));
+	is.get(s, 256, '\n');
+	value = trim(std::string(s));
+	if(name == nm)
+		return value;
+	else
+		goto next;
+}
+
+#undef EOFCHECK
+
+std::string get_setting_default(std::string name, std::istream &is, const std::string def)
+{
+	try {
+		return get_setting(name, is);
+	} catch(std::runtime_error e) {
+		return def;
+	}
+}
+
+DBRedis::DBRedis(const std::string &mapdir)
+{
+	std::ifstream ifs((mapdir + "/world.mt").c_str());
+	if(!ifs.good())
+		throw std::runtime_error("Failed to read world.mt");
+	std::string tmp;
+	try {
+		tmp = get_setting("redis_address", ifs);
+		ifs.seekg(0);
+		hash = get_setting("redis_hash", ifs);
+		ifs.seekg(0);
+	} catch(std::runtime_error e) {
+		throw std::runtime_error("Set redis_address and redis_hash in world.mt to use the redis backend");
+	}
+	const char *addr = tmp.c_str();
+	int port = stoi64(get_setting_default("redis_port", ifs, "6379"));
+	ctx = redisConnect(addr, port);
+	if(!ctx)
+		throw std::runtime_error("Cannot allocate redis context");
+	else if(ctx->err) {
+		std::string err = std::string("Connection error: ") + ctx->errstr;
+		redisFree(ctx);
+		throw std::runtime_error(err);
+	}
+
+	loadPosCache();
+}
+
+
+DBRedis::~DBRedis()
+{
+	redisFree(ctx);
+}
+
+
+std::vector<BlockPos> DBRedis::getBlockPos()
+{
+	return posCache;
+}
+
+
+void DBRedis::loadPosCache()
+{
+	redisReply *reply;
+	reply = (redisReply*) redisCommand(ctx, "HKEYS %s", hash.c_str());
+	if(!reply)
+		throw std::runtime_error(std::string("redis command 'HKEYS %s' failed: ") + ctx->errstr);
+	if(reply->type != REDIS_REPLY_ARRAY)
+		throw std::runtime_error("Failed to get keys from database");
+	for(size_t i = 0; i < reply->elements; i++) {
+		if(!reply->element[i]->type == REDIS_REPLY_STRING)
+			throw std::runtime_error("Got errornous response to 'HKEYS %s' command");
+		posCache.push_back(decodeBlockPos(stoi64(reply->element[i]->str)));
+	}
+	freeReplyObject(reply);
+}
+
+
+void DBRedis::getBlocksOnZ(std::map<int16_t, BlockList> &blocks, int16_t zPos)
+{
+	redisReply *reply;
+	std::string tmp;
+
+	for (std::vector<BlockPos>::iterator it = posCache.begin(); it != posCache.end(); ++it) {
+		if (it->z != zPos) {
+			continue;
+		}
+		tmp = i64tos(encodeBlockPos(*it));
+		reply = (redisReply*) redisCommand(ctx, "HGET %s %s", hash.c_str(), tmp.c_str());
+		if(!reply)
+			throw std::runtime_error(std::string("redis command 'HGET %s %s' failed: ") + ctx->errstr);
+		if (reply->type == REDIS_REPLY_STRING && reply->len != 0) {
+			Block b(*it, ustring((const unsigned char *) reply->str, reply->len));
+			blocks[b.first.x].push_back(b);
+		}
+		freeReplyObject(reply);
+	}
+}
+